It is known to polymerize epoxides at temperatures from about -80.degree.C. to about 250.degree.C. using as catalysts trialkylaluminum compounds complexed with tetrahydrofuran and then reacted with a diketone and water. U.S. Pat. No. 3,642,667 teaches that partial replacement of the diketone with an ether alcohol markedly enhances catalyst activity and life. U.S. Pat. No. 3,135,705 teaches as an epoxide catalyst any organoaluminum compound reacted with water and a chelator such as tetrahydrofuran, a diketone, a hydroxy ester, or the like, but mixtures of the chelators are neither disclosed nor suggested. German Disclosure Document 2,218,243 teaches slurry polymerization of propylene oxide in 4-carbon aliphatic hydrocarbons or in mixtures of 4-carbon aliphatic hydrocarbons with other solvents. The German reference teaches a wide variety of ionic catalysts, such as triethylaluminum, and they are not subject to any special restrictions. A new, more efficient process is desired for slurry polymerization of propylene oxide.